String Theory: The Many Worlds Interpretation

In contrast to the anthropic principle, the many worlds interpretation(MWI) of Hugh Everett III proposes that the wavefunction never actually collapses, but all possibilities become actualities — just in alternate realities. The universe is continually splitting apart as every quantum question is resolved in every possible way across an immense multiverse of parallel universes.

This is one of the most unusual concepts to come out of quantum physics, but it has its own merit. Like the work of Einstein, Everett arrived at this theory in part by taking the mathematics of quantum theory and assuming it could be taken literally. If the equation shows that there are two possibilities, then why not assume that there are two possibilities?

In the case of the Schrödinger’s cat experiment, when you look inside the box, instead of something odd happening to the quantum system, you actually become part of the quantum system. You now exist in two states — one state that has found a dead cat and one state that has found a living cat.

Though these parallel universes sound like the stuff of science fiction, a related concept of parallel universes may arise as a prediction of string theory. In fact, it’s possible that there are a vast number of parallel universes — a vast multiverse.